Optical quantum computers, also known as photonic quantum computers, are a promising approach to quantum computing. They use photons, particles of light, as qubits instead of the more commonly used physical systems like superconducting circuits or trapped ions. Professor Akira Furusawa of the University of Tokyo is indeed a renowned researcher in the field of optical quantum computing.
While it is difficult to definitively state whether it is possible to achieve a billion qubits in an optical quantum computer, it's worth noting that there are several challenges associated with scaling up quantum computers, regardless of the technology being used. These challenges include maintaining qubit coherence, reducing errors, and enabling efficient qubit interactions.
Optical quantum computers have shown promising progress in areas such as quantum communication, quantum cryptography, and small-scale quantum information processing. However, scaling up to a billion qubits is a significant engineering and technical challenge. Currently, the largest number of qubits achieved in any quantum computing platform is in the range of a few hundred, and these are mostly in superconducting qubit-based systems.
It is important to approach any claims of future qubit numbers with a degree of skepticism until concrete evidence and technical details are provided. The field of quantum computing is rapidly evolving, and advancements are being made, but achieving such a large-scale optical quantum computer is a complex task that requires overcoming numerous technical and engineering hurdles. Therefore, it is advisable to follow the latest research and developments in the field to gain a clearer understanding of the current state of optical quantum computing and its potential future capabilities.